Method of manufacturing surface textured high-efficiency radiating devices and devices obtained therefrom

Abstract

A device for emitting radiation at a predetermined wavelength is presented. This device has a cavity with an active layer in which said radiation is generated by charge carrier recombination. The edges of the device define the region or space for radiation and / or charge carrier confinement. At least one of the edges of this cavity has a substantially random grating structure. The edge of the device has substantially random grating structure and can extend as at least one edge of a waveguide forming part of this radiation emitting device. The radiation emitting device of the present invention can have a cavity comprising a radiation confinement space that includes confinement features for the charge carriers confining the charge carriers to a subspace being smaller than the radiation confinement space within the cavity. The emitting device can comprise at least two edges forming, in cross-section, a substantially triangular shape. The angle between these two edges is smaller than 45°. At least one of the two edges has a transparent portion. the devices according to the present invention can be arranged in arrays.

Description

The present invention is related to the field of radiation emitting devices. More in particular semiconductor devices that emit light at a predetermined wavelength with a high efficiency are disclosed. A method of making such devices and applications of the devices are also disclosed.Semiconductor devices that can emit non-coherent or coherent light are known in the art. A number of publications on semiconductor based light emitters deals with Light Emitting Diodes (LEDs) or Microcavity LEDs or Microcavity Lasers or Vertical Cavity Surface Emitting Lasers. Examples of such publications are:H. De Neve, J. Blondelle, R. Baets, P. Demeester, P. Van Daele, G. Borghs, IEEE Photon. Technol. Lett. 7 287 (1995);E. F. Schubert, N. E. J. Hunt, R. J. Malik, M. Micovic, D. L. Miller, "Temperature and Modulation Characteristics of Resonant-Cavity Light-Emitting Diodes", Journal of Lightwave Technology, 14 (7), 1721-1729 (1996);T. Yamauchi and Y. Arakawa, Enhanced and inhibited spontaneous emissi...

AI Technical Summary

Benefits of technology

According to another aim of the invention the outcoupling efficiency of radiation, preferably light, emitting devices is improved, which leads to a reduced power consumption for a given radiation output power.

In a fifth aspect of the present invention, a thin-film light emitting device has a reflective edge such as a metal mirror, preferably dielectric-coated, and an electrical contact is provided through this reflective edge or mirror. The carrier substrate can be located at the mirror side of the thin-film semiconductor device, and light can escape through the opposite side. The carrier substrate can be electrically conductive. It can also be a heat-sink for the LED. Thus according to this fifth aspect of the present invention, light-emitting devices are disclosed having a low-resistance contact path. In this way a high wall-plug efficiency is achieved. Hereto, electrical contacts are foreseen through at least one hole in a mirror side of the light-emitting device. In such embodiment, the mirror preferably is not conductive.

Problems solved by technology

The problem with this technique is that it is inherently slow, because one has to wait for multiple re-absorptions and re-emissions.

Thus there is a problem of making highly efficient light emitting devices as the recombination losses of the charge carriers decrease the efficiency of the total light emission of the devices.

Such devices therefore are not suitable for integration in large arrays.

Also, their large area results in a large capacitance, and therefore slow operation.

Thus the prior art fails to disclose highly efficient light-emitting devices that can be integrated as small devices in a dense array of light emitting devices.

Images